Two suspect entries in excess of $5 billion in the books of confessed fraudster Bernard Madoff have given investigators hope they may be on the trail of some of the money he allegedly stole in what has been called the world's largest financial fraud.

One trail involves secret accounts set up in Switzerland and at an obscure bank in Africa, investigators and lawyers in the case told ABC News.

The investigators and lawyers also tell ABC News that Madoff may have used the name of a dead client, Norman Levy, as well as the prominent Picower Foundation to disguise transfers of more than $10 billion to secret accounts he set up overseas.

Watch the full report Friday on World News with Charles Gibson at 6:30 p.m. ET and 20/20 at 10 p.m. ET

A lawyer who represents both the Levy family and the Picower Foundation, William Zabel, said neither had ever received a $5 billion disbursement or anything close to that amount.

In fact, Zabel said, both families lost millions invested with Madoff. The Picower Foundation and a foundation now run by Levy's family were both forced to close because of their losses.

Investigators caution that the leads could prove to be difficult because Madoff has yet to fully cooperate in the search for the missing billions or in revealing who else may have been involved in the massive fraud.

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"Everything he says is a lie, and we can't count on the veracity of any of his statements or his books," said one of the investigators who has seen the documents. "These five billion dollar entries could also be the way he balanced his books for his losses," said the investigator.

In his confession to the FBI in December, Madoff said he acted alone and that all of the money was gone, that "nothing was left."

EXCLUSIVE VIDEO: Madoff Under House Arrest at his Penthouse

Despite his lack of cooperation, Madoff remains under a luxurious house arrest in his multi-million dollar Manhattan apartment.

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With his window shades up, ABC News cameras saw him spending hours on his computer, appearing to be on the internet, and at other times talking into the computer. There is no restriction on his use of the computer or on computer phone connections, such as Skype.

The new developments in the search for the missing money come as victims attended a briefing Friday in New York by the court-appointed bankruptcy trustee for the Madoff business, Irving Picard.

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Sharing the Pain: Investors Might Now Owe Money

Angry and distraught former investors of Madoff gathered today to receive even more bad news on the hunt for their lost money. Investors may be asked to return past profits they made with Madoff, even if they lost their remaining investment with Madoff. Lawyers for the investors say Madoff did not make any trades on behalf of his clients, that the entire business was a Ponzi scheme.

"We will be seeking to recover false profits from those who received them in substantial amounts," said attorney David Sheehan, who is working with the court-appointed trustee overseeing the liquidation of Madoff's assets.

"There was no stock bought and sold. It was all just made up," he said. "You have to realize you got somebody else's money."